Tests for antibodies to Epstein-Barr viral capsid antigen (EBVCA) or Epstein-Barr nuclear antigen (EBNA) are the most sensitive, are highly specific, and are also the most expensive for diagnosing infectious mononucleosis (strength of recommendation [SOR]: C, based on validating cohort study). Heterophile antibody tests have similar specificity and are cheaper, but are less sensitive in children or in adults during the early days of the illness (SOR: C, based on validating cohort study)
